"Simply put, we all need to have confidence in an assessment system that has so many consequences, and at this point we do not," wrote the Florida Association of District School Superintendents in a statement released Thursday. The association represents the state's 67 school superintendents.

Among the first to raise concerns was Hillsborough County superintendent MaryEllen Elia, who joined four other superintendents representing 40 percent of Florida's students in calling for the audits.

Hillsborough school officials plan a 10 a.m. news conference today to discuss the controversy and the school grades for elementary and middle schools, which are scheduled to be released today. High school grades will be released later.

State officials base the scores on student performance on the Florida Comprehensive Assessment Test.

"We're very concerned that the accuracy of the Florida accountability system be maintained as fair and reliable," Elia said. "We're committed to working with (the Department of Education) to address those issues."

In the statement issued late Thursday, the association said Commissioner of Education Eric J. Smith failed to respond to districts' concerns in auditing this year's elementary reading results. Smith could not be reached for comment. As recently as Wednesday, he expressed confidence in the results.

More than half of the state's school districts reported finding statistical anomalies within the Florida Comprehensive Assessment Test data.

Superintendents believed progress among the lowest-performing fourth- and fifth-graders had not been measured properly — and as a result, the number of elementary schools receiving an A or B would tumble.

Student progress accounts for half of a school's grade.

Scores affect schools on several levels including teacher reassignment and pay, principal evaluation and school recognition funding.

Elia said she is prepared to deal with the fallout if the grades are released.

"Great things have happened in some of our schools," she said. "We're going to take into account multiple years of data so that one day, one test that we have questions about, won't determine how a student is doing."

Hillsborough has been meeting with principals for weeks to get a plan in place and evaluate students case by case, she said.

Frustrations over this year's FCAT results first surfaced in late spring when they were several weeks late. Tensions increased when results arrived. Districts scrutinized them and encountered fluctuations, prompting demands for audits.

School leaders from Miami-Dade, Broward, Duval and Leon counties joined Elia in raising concerns.

But on Thursday, superintendents said several questions initially raised about the results went unanswered. The group urged education officials to settle concerns before releasing grades that would remove "A" status from 300 elementary schools statewide.

"We urge the Florida Department of Education to reconsider the release of school grades until all concerns have been addressed and to proceed with caution as it labels districts, schools, teachers and most importantly, students, with a grading scale which is, at best, controversial and unpredictable," their statement said.